Single Joints – Alloy Steel and Stainless Steel

  • Solid hubs in 14 sizes. Joints 7/8″ and larger have Curtis’ TakeApart feature for easy and economical disassembly and reassembly, with no special tooling required
  • Universal joint hub modifications are available, including bores, keyways, set screw holes, cross pin holes, squares, hexes and splines.
  • Operating angles of up to 35°
Alloy Steel Single Joints

Resources

Single Joint Additional Resources

We stock alloy steel and stainless steel Curtis universal joints in 14 sizes.  Universal Joints 78” and larger have Curtis’ Take-Apart feature which allows for specialized modifications with no special tooling required. This feature makes it easy for the end user to disassemble the joint, machine component parts and reassemble without damaging the hubs, pins or center block.

Alloy Steel Joints

Curtis Alloy Steel Joints feature 4140-grade steel for all forks. Forks of 78 inch diameter and larger have induction-hardened bearing areas for strength and durability. The body (hubs) of the joints remain in an annealed state, which affords free machinability. Center blocks and pins are machined from 8620 alloy steel and are carburized and case hardened to generate superior wear characteristics yet remain ductile, thereby enabling the joint to handle shock loads without experiencing premature failure. Universal joint hub modifications are available per customer specifications, which include but not limited to bores, keyways, set screw holes, cross pin holes, squares, hexes and splines.

  • Alloy steel joints features:
    • 4140-grade steel for all forks. Forks of 7⁄8 inch diameter and larger have induction-hardened bearing areas for strength and durability.
    • Center blocks and pins are machined from 8620 alloy steel and are carburized and case hardened to generate superior wear characteristics

Stainless Steel Joints

Many applications require corrosion resistant universal joints to assure sanitation or to avoid premature oxidation or deterioration. Curtis’ 303 grade stainless steel u-joints are particularly important, for example, to industries that use food processing equipment, and for machinery that comes in contact with corrosive chemicals or is exposed to water for long periods. Furnace applications also benefit from stainless steel, which better withstands high temperatures and other environmental extremes. Curtis stocks 303 stainless in all 14 sizes from 3⁄8″ to 4″. Stainless steel grades 304, 316 and others available by special order.

  • Stainless steel joints features:
    • Corrosion-resistant to assure sanitation or to avoid premature oxidation or deterioration
    • 18-8 Type 303 Stainless, non-magnetic steel
    • Dimensionally the same as alloy steel joints, except for OD tolerance

Features of the Curtis single joints:

  • Extra angularity allows standard units to operate at angles up to 70°
  • Firm, positive lockup of the entire assembly thanks to Curtis’ exclusive Tell-Tale Lock Ring
  • Built-in lubrication passages with Curtis’ exclusive internal lubrication system
  • Lubrication covers (boots) available in all sizes to retain lubrication and keep out contaminants, extending the life of the joint. Curtis Joints do not require grooves on hubs to retain boots
  • Less galling and seizing because Curtis uses dissimilar materials on all bearing surfaces
  • Maximum wear and strength from Curtis’ induction hardened forks
  • Easy machinability due to Curtis’ soft hubs
  • Smooth operations and longer life assured by close and well-controlled tolerances between mating parts and Curtis’ built-in lubrication system
  • Perfect concentricity with hubs ground on center and centering holes provided on solid hubs to aid in machining
  • Universal joint hub modifications are available, including bores, keyways, set screw holes, cross pin holes, squares, hexes and splines

For assistance in ordering your universal joints, please refer to Curtis’ how to order instructions or contact the Curtis sales department for more information.

Universal Application Examples

  • Stock Car Racers
  • Nuclear Installations
  • Tractor Attachments
  • In-Plant Utility Vehicles
  • Grain Augers
  • Boiler Damper Controls
  • Bottle Capping
  • Surgical Tables
  • Submarine Periscopes
  • Paper Making Equipment

Alloy and Stainless steel joints are dimensionally the same except for O.D. tolerance

  • Alloy steel O.D. tolerance is +.000-.003″
  • Stainless steel O.D. tolerance is +/- .020″

NOTE #1. Large bearing pin is provided with an oil passage. The 1.00″ through 4.00″ diameter joints are also fitted with a ball spring oil fitting to retain lubricant.

NOTE #2. Curtis standard single universal joints will operate through angles of 35°. For applications requiring greater angles, special design can be employed, enabling the joint to operate at angles up to 45°.

Model

Outside Diameter

Bore Diameter

Total Length

Centerline to End

Hub/Bore Length

Set Screw Size

Keyway Size

Far Side to Bottom of KW

Shaft to Shaft Distance

A

B

C

C/2

D

E

F

G

H

CJ641

CJ641B

CJ641B1SS

3/8

---

3/16

3/16

1.750

0.875

11/16

---

---

2-56 NC

---

---

---

---

---

---

3/8

CJ642

CJ642B

CJ642B1SS

1/2

---

1/4

1/4

2.000

1.000

3/4

---

---

4-40 NC

---

---

---

---

---

---

1/2

CJ643

CJ643B

CJ643BKW1SS

5/8

---

5/16

5/16

2.250

1.125

13/16

---

---

10-32 NF

---

---

3/32x3/64

---

---

.352

5/8

CJ644

CJ644B

CJ644BKW1SS

3/4

---

3/8

3/8

2.688

1.344

31/32

---

---

10-32 NF

---

---

3/32x3/64

---

---

.416

3/4

CJ645

CJ645B

CJ645BKW1SS

7/8

---

7/16

7/16

3.000

1.500

1-1/32

---

---

10-32 NF

---

---

3/32x3/64

---

---

.480

15/16

CJ646

CJ646B

CJ646BKW1SS

1

----

1/2

1/2

3.375

1.688

1-3/16

---

---

1/4-20 NC

---

---

1/8x1/16

---

---

.555

1

CJ647

CJ647B

CJ647BKW1SS

1-1/8

---

9/16

9/16

3.500

1.750

1-7/32

---

---

1/4-20 NC

---

---

1/8x1/16

---

---

.618

1

CJ648

CJ648B

CJ648BKW1SS

1-1/4

---

5/8

5/8

3.750

1.875

1-1/4

---

---

5/16-18 NC

---

---

3/16x3/32

---

---

.705

1-1/4

CJ650

CJ650B

CJ650BKW1SS

1-1/2

---

3/4

3/4

4.250

2.125

1-11/32

---

---

5/16-18 NC

---

---

3/16x3/32

---

---

.832

1-9/16

CJ651

CJ651B

CJ651BKW1SS

1-3/4

---

7/8

7/8

5.000

2.500

1-9/16

---

---

5/16-18 NC

---

---

3/16x3/32

---

---

.958

1-7/8

CJ652

CJ652B

CJ652BKW1SS

2

---

1

1

5.438

2.719

1-5/8

---

---

3/8-16 NC

---

---

1/4x1/8

---

---

1.109

2-3/16

CJ653

CJ653B

CJ653BKW1SS

2-1/2

---

1-1/4

1-1/4

7.000

3.500

2-3/32

---

---

3/8-16 NC

---

---

1/4x1/8

---

---

1.363

2-13/16

CJ654

CJ654B

CJ654BKW1SS

3

---

1-1/2

1-1/2

9.000

4.500

2-27/32

---

---

1/2-13 NC

---

---

3/8x3/16

---

---

1.663

3-5/16

CJ655

CJ655B

CJ655BKW1SS

4

---

2

2

10.625

5.313

3-1/8

---

---

1/2-13 NC

---

---

1/2x1/4

---

---

2.219

4-3/8

Alloy Steel 303 Stainless Steel
Joint Diameter Max. Static Torque Inch Pounds
3/8″ 140 100
1/2″ 425 375
5/8″ 900 610
3/4″ 1610 1000
7/8″ 1800 1350
1″ 3050 1900
1-1/8″ 3500 2200
1-1/4″ 5500 3600
1-1/2″ 9000 7200
1-3/4″ 14000 10700
2″ 22000 15500
2-1/2″ 32000 21000
3″ 55000 34000
4″ 131000 81000